ABSTRACT Similar to other Western U.S. cities, air quality in Reno, NV is routinely impacted by smoke from wildland fires. Smoke plumes contain complex air pollutant mixtures, and their aerosol composition is governed by several factors. These factors include aging, in which secondary organic aerosols are formed when biomass burning emissions undergo atmospheric oxidation, and fuel type (i.e., the type of vegetation burned). Residents throughout the West are also exposed to smoke from prescribed burns, which are used by land managers to mitigate wildfire risks. Due to their lower intensity, prescribed burns are more likely to smolder, and emissions from smoldering fires differ from those of flaming fires. To model the aerosol composition of smoke plume mixtures in the West requires detailed emissions information from regionally relevant fuels, accurate characterization of aerosol aging, and consideration of differences between low intensity prescribed burns and flaming wildfires. In 2006, the major health care provider in Reno (Renown Health) transitioned to electronic medical records (EMRs). At present, this database contains information on over 1.4 million patient visits. This resource, combined with Reno?s frequent exposure to smoke from fires that originate from ecosystems impacting many major Western U.S. cities, make Reno an opportune setting to investigate associations between smoke plume mixtures and population health. Our proposed study has two overarching goals. 1) We will improve smoke exposure modeling in the West for use in public health applications. We will create a new, innovative air quality model that will be the first to use tailored emissions information from regional biomass fuels to model smoke plume mixtures, which will vary according to the ecosystem of origin, atmospheric aging, and fire intensity (low intensity prescribed burns vs. flaming wildfires). 2) We will advance understanding of the acute population-level health effects of smoke exposures. We will perform an epidemiologic investigation using the Renown EMRs, considering overall associations and potential heterogeneity by smoke plume mixtures. We will estimate associations of smoke exposures with four broad categories of health outcomes (acute upper airway disease, acute lower airway disease, acute cardiovascular disease, and maternal blood pressure) and with specific acute conditions of a priori interest within these categories (i.e., asthma, bronchitis, COPD exacerbation, pneumonia, congestive heart failure exacerbation, ischemic stroke, and myocardial infarction). Anticipated outcomes include improving our ability to model smoke plume mixtures for biomass burning events that impact millions of Americans annually and are projected to increase in the future. We will provide the first health association estimates for prescribed burns, which will be of immediate use to land managers and other stakeholders in the natural resources and public policy arenas. We will also provide the first estimates of potential heterogeneity in population health outcomes by smoke plume mixtures. Longer-term, our study will help to inform the development of more accurate, evidence-based public health warning systems.